I. Field of the Invention
The invention relates generally to an improvement to a mechanism for preventing flooding or overflows in holding tanks and receptacles. It more particularly relates to an improved flood level sensor for sensing overflows in toilets of the type used in correctional institutions, however, the invention is capable of significantly wider application.
II. Description of the Prior Art
In recent years, greater attention has been paid to the expansion and renovation of prisons and other correctional facilities. It has been the experience in such facilities that inmates will sometimes attempt to disrupt normal operations by stuffing clothes or other objects into a toilet bowl and repeatedly flushing the toilet to cause its flooding. This can result in substantial property damage, and if the living units in which the toilets are located are on an upper floor, the overflow may find its way to offices, archives or other installations below. Toilets in such facilities must be tamper-resistant in order to prevent these occurrences.
Various devices have been proposed to prevent either accidental or deliberate flooding of toilets. For example, U.S. Pat. Nos. 1,815,384; 1,956,086; and 1,956,087 all granted to M. J. Tracy, show the use of floats for level sensing in several systems for mechanically disabling toilet flush mechanisms. In each of these patents, the float is located in an auxiliary compartment in which the fluid level rises with the fluid level in the toilet bowl. Similarly, Finley, U.S. Pat. No. 2,080,073 also shows a mechanical float in an auxiliary compartment. As the float rises, the level of mercury in a third compartment is lowered, to break a vacuum created by a toilet siphon and interupt the flow from a reservoir tank to a toilet bowl. Luker et al, U.S. Pat. No. 4,402,093 shows a movable valve element that is manually positioned between a toilet reservoir tank and a toilet bowl, if it appears that the toilet bowl is ready to overflow, to interrupt flow from the tank to the bowl.
A copending U.S. patent application of Barnum et al, Ser. No. 608,392, filed May 9, 1984, and entitled "Flood Preventer for Fluid Filling Systems", discloses a lockout mechanism that is inserted between a toilet flush valve and a valve actuator button to prevent repeated flush cycles when flooding of the toilet is sensed. A partial vacuum is generated during each flush cycle, and unless relieved through an orifice, the partial vacuum will operate the lockout mechanism. By positioning the orifice at a selected level in the toilet bowl, the flush valve can be "locked out" when the water reaches that level and partially seals the orifice--thereby preventing relief of the vacuum.
In this prior system, the level sensing orifice was accessible to occupants of the facilities in which it was installed. When the orifice was located within the toilet rim, there was a problem of excessive water being drawn into the vacuum lines due to the strong vacuum generated during flush cycles. It was in this environment that the present invention was made.